<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            width:400px;
            height:50px;
            background-color: aqua;
        }
        @keyframes move {
            0%{
                transform: translateX(0px);
            }
            100%{
                transform: translateX(-400px);
            }
        }
        .run{
            animation: 1s move linear reverse;
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>